I'm glad you are trying anti-depressants. Although they won't fix the underlying problem, they can help. I think you know the reasons why you do it, you just don't know what to do about it. I wish I could say something to help, but I have nothing right now, except I know how you feel. And your wife seeking love elsewhere has way less to do with you, and more to do with her internal struggles. I hope your therapist can help you find other coping skills.

P.S. As much as it hurts reading your struggles, in a couple months it will be 8 years for me, and it is an important reminder that all it takes is one cut for it to go right back to the way it was for me.